html{
    font-size: 62.5%;
}

body{
    font-size: 10px;
}

.value_px{
    font-size: 2em;
}

.value_em{
    font-size:2em;
}

.value_rem{
    font-size: 2rem;
}

/* 颜色值 */
.color_name{
    color:red;
}

.color_hex{
    color:#00ff00;
}

.color_fun{
    color:rgb(0,0,255);
}

/* 图片函数 */
.img_url{
    width:500px;
    height:100px;
    background-image: url("qq_logo.webp");
    background-repeat: no-repeat;
}

/* 字体样式属性 */
.font_demo{
    color: red;
    font-size: 2em;
    /* font-family:'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif; */
    font-family:"宋体" Arial, Helvetica, sans-serif,serif,monospace;
    font-style: italic;
    font-weight: 1000%;
}

/* 常见文本样式属性 */
.text_demo{
    font-size: 2em;
    border: 1px solid black;
    width: 50rem;
    height:10rem;
    text-align: left;
    line-height: 10rem;
    text-decoration: underline;
    text-indent: 3rem;
    letter-spacing: 1rem;
    word-spacing: 2rem;
}

/* 列表样式属性 */
ul{
    font-size:2rem;
}

.list_demo1{
    list-style: circle inside;
}
.list_demo2{
    list-style: none;
    
}
.list_demo3{
    list-style-image: url("qq_logo.webp");
    list-style-type: none;
    list-style-position: inside;
}

.list_demo4{
    list-style: none url("qq_logo.webp") inside;
}

.bg_box{
    border: 3px solid red;
    width: 50rem;
    height:15rem;
    
}
.bg_demo1{
    background-color: orange;
}

.bg_demo2{
    background: url(qq_logo.webp);
    
}
.bg_demo3{
    background: url(qq_logo.webp);
    background-repeat: no-repeat;
    background-position:top center;
}
.bg_demo5{
    background: url(qq_logo.webp);
    background-repeat: no-repeat;
    background-position:top right;
    background-attachment:fixed;
}

.bg_demo6{
    background: #d1e7d1 url(qq_logo.webp) no-repeat top right fixed;
}

/* 表格样式 */
.table_demo{
    font-size:2rem;
    border: 1px solid black;
    width: 70%;
    margin: 0 auto;
    table-layout: fixed;
    border-collapse: collapse;
    border-spacing: 10px;
    caption-side: top;
    empty-cells: show;
}

.table_demo th, .table_demo td{
    border: 1px solid black;
    text-align: center;
}

.table_demo tbody{
    background-color:rgba(153, 41, 41, 0.584);
    color:white;
}

.table_demo tbody tr:hover{
    background:rgb(88, 177, 78);
    cursor:pointer;
}
.table_demo caption{
    font-size: 3rem;
}
.table_demo tfoot td{
    text-align: right;
    padding-right: white;
}

/* 表单样式 */
.form_demo{
    font-size: 2rem;
    border: 1px solid seagreen;
    background: #fff;
    width: 35rem;
    height: 25rem;
    text-align: center;
}
.form_demo input[type="text"] ,.form_demo input[type="password"]{
    border-left:0;
    border-right: 0;
    border-top: 0;
    border: 1px solid #000;
    width: 200px;
    height:39px;
    padding-left: 39px;

}
.form_demo #username{
    background: #fff url(images/username.png) no-repeat top left;
    
}

.form_demo #pwd{
    background: white url(images/password.png) no-repeat top left;
}

.form_demo input[type="submit"]{
    width: 100px;
    height: 38px;
    background-color: rgb(137, 127, 127);
    border: 1px dashed rgb(59, 119, 179);
    letter-spacing: 10px;
    color:aliceblue;
    
}